Background/Aims To assess whether mean deviation (MD) from automated perimetry is related to the visual field (VF) component for legal fitness to drive (LFTD) in glaucoma patients.
Methods Monocular 24-2 VFs of 2604 patients with bilateral VF damage were retrospectively investigated. Integrated visual fields were calculated and used as a surrogate to assess LFTD according to current UK driving licence criteria. The better eye MD (BEMD), worse eye MD (WEMD) and a measure utilising MD of both eyes were compared, to assess respective diagnostic capabilities to predict LFTD (using the integrated visual field surrogate test as the gold standard) and a ‘Probability of Failure’ (PoF) for various defect levels was calculated.
Results BEMD appears to be a good predictor of the VF component for a patient's LFTD (receiver operating characteristic area under the curve: 96.2%); MDs from both eyes offered no significant extra diagnostic power (area under the curve: 96.4%). PoF for BEMD thresholds of ≤−10 dB and ≤−14 dB were 70 (95% CI 66% to 74%) and 92% (87% to 95%), respectively.
Conclusion There is a strong relationship between BEMD and a patient's LFTD. PoF values for LFTD associated with readily available MD values provide practical landmarks for VF disability in glaucoma.
- Visual field
- visual impairment
- optic nerve
- field of vision
- intraocular pressure
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Funding This work was funded in part by the UK National Institute for Health Research (NIHR) Health Services Research programme (project number 10/2000/68). Crabb's research laboratory at City University in London is supported in part by unrestricted funding from Allergan Ltd and the Investigator-Initiated Studies Programme of Merck Sharp & Dohme Limited.
Competing interests None.
Patient consent Patient database investigated was anonymised.
Ethics approval The Research and Ethics committee of the Department of Optometry and Visual science at City University.
Provenance and peer review Not commissioned; externally peer reviewed.